1. Field of the Invention
The present invention relates to an optical lens assembly for image capture, and more particularly to an optical lens assembly for image capture comprising three lens elements and the optical lens assembly is applied to an electronic product.
2. Description of the Related Art
Optical lens assembly for image capture is usually installed to a mini electronic device such as a digital still camera, a mobile phone camera and a web camera for capturing images of an object. The optical lens assembly for image capture tends to be developed with compact size, low cost, good aberration correction, high resolution, and high image quality.
In general, a conventional optical lens assembly for image capture for mini electronic products comes with different designs, including the two-lens, three-lens, four-lens, and five-or-more lens designs. Although the optical lens assemblies with the four-lens and five-lens designs have advantages on aberration correction and modulation transfer function (MTF) performance, yet they incur a higher cost. On the other hand, the optical lens assemblies with the two-lens design incur a lower cost, but they usually fail to meet the high-resolution requirements. Therefore, the optical lens assemblies with the three-lens design as disclosed in U.S. Pat. No. 7,468,847 and U.S. Pat. No. 7,679,841 and WIPO patent of WO2010026689 are preferred.
In the optical lens assembly for image capture with the three-lens design, the third lens element in proximity to the image plane always plays a role providing higher aberration ability and higher refractive power, and the bi-convex third lens element can provide higher refractive power. The bi-convex third lens element with positive refractive power as disclosed in U.S. Pat. No. 7,710,662, U.S. Pat. No. 7,423,817 and U.S. Pat. No. 7,301,712 adopts a combination design of positive refractive power, negative refractive power and positive refractive power. However, the first lens element disclosed in these patents provides insufficient positive refractive power near the object side and fails to collect more light, or the second lens element with negative refractive power has insufficient refractive power and hardly corrects the light collected by the first lens element. Therefore, the present invention provides a feasible design and adopts a combination of refractive powers of the three lens elements and a combination of convex and concave lens elements to achieve the effects of providing a high image quality, facilitating mass production to lower the cost, and applying the optical lens assembly to electronic products.